This invention relates generally to a hose assembly employing a hydroformed fitting, and more particularly, to an improved hydroforming system and method of using a die to hydroform a hose fitting.
Hydroforming, sometimes referred to as fluid forming, was developed during the late 1940s-early 50s in response to a need for a more efficient, cost-effective method of producing metal parts. As a general principle, hydroforming involves application of a predetermined fluid pressure to an area of metal surface to be manipulated. Where the metal surface is a tube, an internal fluid pressure is applied as the tube is bent and stretched. Generally, hydroformation of a tube can be accomplished by filling the tube interior with the fluid, retaining it therein and increasing the internal pressure. Depending upon the die tool utilized, hydroforming can also be used to radially expand the tube.
Specific advantages of hydroforming include: relatively inexpensive tooling, the availability of complex shapes and contours, minimal material thinout (hydroforming flows the metal rather than stretching it--thinout is usually less than 10%), reduced finishing costs (by comparison, matched die methods of formation can cause scuff marks, shock and stretch lines), and precision with difficult configurations even where high tolerances are required.
Typically, fittings manufactured for use in conjunction with hose assemblies are machined at considerable expense. Where a one-piece machined fitting is not available or is uneconomical, a brazing procedure can be utilized to provide the desired fitting from two components. Inherently, brazing provides a structural weakness which may manifest itself through failure upon application of routine pressure forces. Where one-piece fittings can be machined, they are difficult to bend if a curved configuration is required. Even so, bending introduces material weaknesses and increases the potential for failure at application pressures.
There are a considerable number of problems and deficiencies relating to the manufacture of hose fittings and, subsequently, assemblies with such fittings. The search for a cost-efficient and effective alternative to machining has been an on-going concern in the art. There is a need for a system/method, hose fitting and/or assembly which takes advantage of the manufacturing and commercial benefits typically associated with hydroforming.